Bushnells are still good scopes. If you truly did have some loose screws on the gun, then that should be your problem. I too use a boresighter in my basement to get me on paper with non bolt guns. With bolt guns, I put it in a gun vise, take the bolt out and look through the barrel at a pumpkin or large object about 75-100 yards away. Center it in my barrel and then very carefully adjust the crosshairs so they are now on the object. This will get you on paper also (I actually like this way better than a laser boresighter).

Now, when you go shoot the gun to sight it in, you can do it in one shot. Here's how. Using a gun vise to steady the gun, adjust it so it is dead center on your target at a distance that you can see your hole after you shoot. Take the shot from the vise with as little influence by you as possible to ensure that you don't flinch. After the shot, align the gun back to where you had before the shot (meaning the crosshairs centered on the target), while you are looking through the scope, adjust the crosshairs to where the shot actually went. This will now put the crosshairs and the actual point of impact at the same spot. You should shoot the gun again to ensure that it is fine tuned, but it should be dead zero. I read this method in a gun magazine many moons ago and have used it every time I mount a new scope and it works like a charm.